Process of making dextrose



May 18, 1943. J. F. WALSH Erm. 2,319,648

PROCESS OF MAKING DEXTROSE Filed Sept. 25, 1940 James f ,Wa/sk Jaffa/5uriirlel' INVENTORS BY f ATTORNEY Patented May 18, 1943 i UNITED- STATEs PATENT. l'OFFICE'.

PROCESS OF MAKING DEXTROSE James'F. Walsh, Yonkers, N. Y., and JamesDudicker, Hammond, Ind., assignors to American Maize-'Products CovMaine." v

mpany, a' corporation of Appucaaon'september 25,1940, serie1No.35s,27z

s claims. 1 (ci. 12v- 40) conversion of the carbohydrates of themolasses This invention relatesto a method 'of making dextrose. Moreparticularly,fthe invention .re' lates to the conversion of starchcrystallized dextrosevwith much higher yields than have been possibleheretofore.

. In the usual method of making dextrose, starch is suspended in water,hydrolyzed with acid, the

resulting syrupi neutralized to the desired PH. and thesyrup thendecolorized andevaporated to a suitable concentration'V for subsequentcrystallization of dextrose. The concentrated syrup is then allowed tocool so that as much as possible ofy the dextrose present iscrystallized. The remaining motherv liquor is separated from thecrystals, as by centrifuging, to'give a crude molasses. The crystallizeddextrose is ordinarily washed withwater. I v

'The' molasses separated from the .dextrose crystals, in this lusualmethod for making dextrose, contains an important part ofthe total ofthe starch conversion products.

Attempts have been made to obtain increased tions, by eitherreconversion-of the molasses or by repeatedV reconcentrations andrecrystallizations of the molasses. Neither of these methods have provenpractical in giving the desired yield of dextrose of satisfactory Ilquality. Recoveries of dextrose have been low, the cost of processinghigh, and the time cycles involved excessively' long in the recovery,the yields vranging from about 70 to -85% at the best, the material lostin the molasses being chiefly useful only in markets where theaccumulated coloring matters, impurities, and bitter principlesresulting from the process are acceptable in view -of the low priceobtained for the material.

' Also, attempts have been made to utilize the starch sugar molasses, byreturning it to the system as partl ofthe total suspension going toconversion. Thus, it has been attempted to mix the molasses with." freshstarch previous to con# yields of dextrose from starch conversionsoluversion. ,4 This method? of use has proven un'satis-y factory, /dueto a substantial, extent to the ash (inorganic salts) contentwhichinterferes with conversion and tends to inhibit satisfactorycrystallization of dextrose, after repeated reuse .a of the molasses.

'I'he present invention provides a method by which 'starch is convertedto dextrose with ex-` cllent yields and the production of no substantialamount of low pricedvby-products. This result is'accomplished by amethod including treatment of the crude molasses so as to removematerial which, if not removed, interferes with the y remo to dextroseand subsequent crystallization of the dextrose.

Briey stated, the invention comprises forming the'crysltallized dextroseand crude molasses as described above, treating the crude molasses so asto remove sodium vand other metals present, reconverting the treatedmolasses, and crystallizing dextrose therefrom. ment of the invention,the molasses refined bythe al of the metals is returned to the acidconversion step and there mixed withl fresh starch in the standardprocess. According, to the invention, the molasses are so purified thatthe solids therein do not interfere with the conversion of starch.

Once the process is oper ting regularly, the batch for acid conversionwi' contain not only fresh starch but also a' certain amount ofthe renedmolasses. i

The water used vto wash the crystallized dextrose is also utilized, aswill appear later.

There is thus provided a process which is of the nature of a closedoperation, only the desired. crystallized dextrose being taken from thesystem in any substantial amount.` As a result, loss oi' starch in theform of by-products is practically eliminated. It will be understood,however, that proteins are also produced and separated in substantialamounts, in this case the starchy material used as raw material containsmuch pro-y j v v To remove .from the molasses the sodium and othermetals which,.if present, interfere with the conversion 'of maltose,dextrins, and the likein the molasses or with subsequent crystallizationof dextrose,there is used a base exchanger. which has the property ofremoving from anaqueous solution,"in this case the molasses, a largepart of the alkali metal' and other metals present in the solution inthe form of their salts. f

The 'most abundant of these metals-in the masses is ordhiarny that onewhich is added in Because of the amount oiacid to be neutralized In thepreferred embodif For this neutralizing of the alkali metal in theneutralized syrup is of the order of about 0.5 to 1% of the weight ofdissolved solids. 'I'he proportion of such alkali metal in the syrup is,therefore, large in proportion to the amount of the other metalspresent.

It will be evident, also, that the alkali metal salt resulting from theneutralization of the acid employed in the conversion will remaindissolved and appear in the molasses separated from the dextrosecrystals.

To remove the alkali metal and other interfering metals from themolasses, there is utilized preferably a base exchanger of special type,say, a hydrogen zeolite, the term zeolite vbeing used' herein to includethe so-called organolitea Among such base exchangers that may be usedare those conventionally employed for removing sodium and other alkalimetals from aqueous' solutions of their salts, materials that functionin part at least by the exchange of hydrogen for sodium or other metal.frequently are slightly acidic, so as to give a pH somewhat below 'I inthe molasses at the time that`v it is in contact with the zeolite.

In addition to the .property of removing the major portion of sodium andother metals present in the molasses, the exchanger used should benon-color-throwing and a non-supporter of the growth of fungi and molds.

Among the zeolites that meet these general requirements and that havebeen used to advantage is the activated organic material produced bytreatment of coal, lignite, or wood by the process described by Tiger inTransactions of the American Institute of Mechanical Engineers, 60, No.11, 315-325 (1938). Such material is known commercially as Zeo-Karb H.This base exchanger has the capacity to .remove various amounts up toabout '7000 grains cr somewhat more of sodium or other metals fromsolutions passedslowly over the material, for each cubic foot of thematerial. The Zeo-Kar-b H is preferably used under such conditions as toacidity that the solution in contact'with the Zeo-Karb is acid tophenolphthalein, say of pH value below 8.3, preferably 4.5 to 6.

. which remove alkali metal from an'aqueous so-' lution of its salts andthat do not introduce into the molasses solution treated any substantialamount of interfering water soluble by-products.

Acidity is not considered an interfering substance, as acidity iscompensated for in the amount of acid added for reconversion, or may beneutralized.

The base exchanger selected is preferably used in granular form andfilled into a container or tower. The-molasses to. be purified is causedto flow slowly through the bed of the base exchanger, at such a ratethat the time of contact with the base exchanger is substantial, Asay 1to 4- hours.

The base exchanger is separated from the treated (refined) "molasses, asby the passage of Such hydrogen zeolites` 2,819,648 by the alkali metalalkali, the content of the salt 'I the molasses through and out of thecontainer for the exchanger, as described.

For best results, the molasses are diluted before treatment with thebase exchanger. Thus, the

crude molasses may be diluted to about the same' concentration, in termsof total solids, as pre; vails in the fresh starch suspension to whichthe molasses after the zeolite treatment are preferably added.

A typical example of the practice of the invention will be illustratedin connection with the attached drawing which shows a suitable sequenceof steps in our method.

Starchy material', such as rened starch from potatoes, corn, wheat, orbarley, or an impure material such as table head starch, is made into asuspension with water and converted by hydrolysis in the presence ofacid. Thus, the starch may be made into an aqueous suspension of densityabout 12 to 16 B., hydrochloric-acid added,A and conversion under steampressure effected. i

all in accordance with usual procedure.

During this conversion, dextrose is formed, the conditions of conversionselected giving as high a yield of dextrose as practicable without theintroduction of objectionable decomposition and reversion products, suchas excessive amounts oi' y conversion syrup, is treated with sodimcarbonate or other suitable alkali, ordinarily an alkali metal alkali,to adjust the pH to that.- desired. This is commonly called theneutralization step, the neutralization being effected in a typicalprocedure to the extent 'that the pH is raised to about 4.0 to 5.5.

During the neutralization, certain materials that coagulate onadjustmentof the pH are separated, particularly the coagulable proteinsland fats. These coagulated products are removed by filtration and thusmade ready forsale, as

for use in the compounding of feeds.

'The filtrate from the coagulated material is ordinarily called lightliquor.

Ihe light liquor is decolorized in conventionalv manner, as by passageover animal or vegetable decolorizing carbon. The liquor is thenconcentrated, say, to about 30 B.' in evaporators for light liquor, theconcentration being carried tol about 30 to 31 B.

The liquor after concentration is suitably de.l

colorized again with animal or vegetable carbon. In any case, the liquoris concentrated finally to a very high degree, favoring thecrystallization oi the dextrose in as large proportion as possible whenthe highly concentrated liquor is cooled. For this reason, the finalconcentra-v` tion may be continued in an evaporator until the density ofthe liquor is about 39 to 40 B.

The concentrated liquor is then transferred toa crystallizer, in whichcrystallizationlof dextrose is eected in usual manner. Thus, theconcentrated liquor may be charged into the crystal' lizer whichcontains initially a certain amount` suitably 4 to 5 days during whichtime the temperature falls from about 120 'to around 75 F.

The resulting massecuite, -including crystals and molasses'as the motherliquor, is centrifuged, the molasses being removed by the centrifugalaction.

The dextrose crystals in the centrifuge are then washed with water, thefirst portion of the eillu'- ent Ibeing combined with the molassesfraction until the purity of theeflliient becomesv at least 85 D. E.`When this stage 'is reached, then the later portions Aof wash water arediverted to a previous step in the process preceding theevaporation;suitably the-wash water of 85 purity or more is added to the lightliquorpassing into thel light liquor decolorizer. v

When the waterwashing is completed, the dextrose is discharged from thecentrifuge and dried, the dried material being ordinarily 99 1to 100% D.E.

of solids to dextrose. The molasses is first diluted. if desired tolowerthe viscosity, say to about 12 to 16 B., and'- is caused to pass slowlyover the base exchanger of the kind described. The base exchanger issupported to advantage in a tall vessel and the crude molasses vpassedvertically through the vessel. By controlling the outlet valve, the rateof flow of the molasses through the exchanger is s o regulated that thedesired period 4 of Icontact between the molasses being refined and thebase exchanger is established.

The molasses after treatment with the base exchanger is preferablydecolorized,- as by anima or vegetable carbon in usual manner.

In any case, the.treated molasses are subjected to acid conversion so asto transform a large part of'the maltose and dextrins therein todextrose; 'I'he thus converted molasses are neutralized,

to crystallize a dextrose fraction which is sep- Brated r.from theremaining mother liquor as described previously. This second portion ofmother liquor separated from dextrose is retreated as Preferably,however, the refined molasses are not treated separately ,but areremixed into the system with fresh starch to be converted, sothat themolasses -go through vthesame' sequence o f `steps as does' freshstarch, beginning with the acid conversion. 1 This combining of therefined molasses wit starch is made possible because, in the molassestreated with the base exchanger, there .are not present materials whichinterfere to an objectionable extent with the conversion or subsequentcrystallization of the dextrose.

While it is considered that thefexchange of -hydrogen of thebaseexchanger for metals press ent in the form of their, dissolved salts inthe l 'Ihe crude molasses separated as describedy above is now treatedto remove from the molasses substances which. interfere with theconversion concentrated say to about 39 `to 40 B. and cooled to thel`light liquor decolorizer and the molasses are .returned to the make-uptank for fresh starch, we have obtained practically theoretical' yieldsof crystallized dextrose from starch.

For some purposes, the alkali metal alkali in the neutralization stepfollowing conversion may be replaced Iby finely divided calciumcarbonate, lime, magnesia, or like alkali. In such a case, thel Y :baseexchanger treatment applied to the resulting s molasses removes thecalcium, magnesium, Vor other metal added in the neutralization, withattendant improvement in yield of dextrose of satis-4 factory qualitywhen the purified molasses are retiuned to conversion and reworked, asdescribed above. 4

When compounds of metals other than the alkali metals are used for theneutralization after conversion, the acid selected for use in making theconversion should be one whose salts with calcium, magnesium, and likemetals are soluble. Thus, the acid used may be hydrochloric, acetic,

' or nitric acid, the latter i'f used being added in very dilute form.

It will .be understood that the details given are for the purpose ofillustration and that variations within thev spirit of the invention areintendedto be included within the scope of the appended claims. y

What we claim is:

1. The method of converting starch of starchy materials substantiallycompletelyv to crystallized dextrose which comprises converting thestarch to dextrose and other products by hydrolysis in the presence ofwater and acid, treating the resulting conversion syrup with an alkalilto increase the pH and coagulate proteins and other coagulablesubstances, the said acid and alkali used being ones that on reactionwith each other give only a-salt that is soluble in water, removing thecoagulated material, decolorizing and concentratingythe remaining liquorso as to give a concentrated refined syrup, crystallizing ldextrose fromthe concentrated syrup, Separating mother liquor as crude molasses fromthe crystallized dextrose, treating the separated molasses with a baseexchanger adapted to remove metals from an aqueous solution of saltsofthe metals and replace the said metals by hydrogen, so as to effectreduction of the content of metals in the molasses is a chief factor inthe molasses refining operation,v the invention is notl limited vto anytheory of explanation of the /results obtained.

Ther invention makes use on the other hanld of all results obtained bythe `method described which result in the refining of the molassesl sothat it'maybe converted by acid with a good yield of dextrose and withut the introduction of ex cessive amounts of bi ter or otherwiseobiectionable materials, whether the reflnedmolasses are converted b'ythemselves or are mixed with fresh starch before conversion. f v

By following the method described and particularly that in which thewash water is returned f' molasses, separating the base exchanger fromthe treated molasses, subjecting the treated molasses to the;aforesaidsteps beginning with the. acid conversion and repeating the cycle ofsteps until vsubstantially all the starch conversion products areobtained as crystallized dextrose, the removal of -metals by theexchanger serving to improve `issoluble in water, removing thecoagulated material, decolorizing vand concentrating the remain'inglliquor so vas to give concentrated refined syrup, crystallizingdextrose from the concentrated syrup separating mother liquor as crudemolasses from the crystallized dextrose, treating the separated molasseswith a Ibase exchanger adapted to remove metals from an aqueous solutionof salts of. the metals and replace the said metals base exchanger fromthe treated molasses, mixing the treated molasses with fresh starchsuspension, and repeating the aforesaidsequence of steps beginning withconverting the starch, the removal of metals by the exchanger serving toimprove the conversion of the molasses to dextrose.

3. The method described in claim 2, the alkali exchanger removing alkalimetal and other metals from the crude.` molasses, and the molasses beingdiluted to about 12 to 16 B. before being contacted with the baseexchanger.

4. The method described in claim 1, the base exchanger used being anactivated organic mate- V rial, the treatment of the molasses with thebase exchanger being effected at a temperature between about 125 and 175F., and the treatment being continued for a substantial period of timeuntil the activated organic material has removed 5 the major portion -ofthe metals from the molasses. v

5. 'I'he method described in claim 1, the alkali used to treat the saidconversion syrup and increase the pH being calcium hydroxide and the l0acid used initially to effect `the conversion of used being an alkalimetal compound, the base the starch to dextrose and other .products byhydrolysis being hydrochloric acid so that there is avoidedprecipitation of calcium when the calcium hydroxide is added and duringconcen- 15 trating of the syrup.

JAMES F. WALSH. JAMES DUDICKER.

